/*
The nth term of the sequence of triangle numbers is given by, tn = ½n(n+1); so the first ten triangle numbers are:
1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
By converting each letter in a word to a number corresponding to its alphabetical position and adding these values we form a word value. For example, the word value for SKY is 19 + 11 + 25 = 55 = t10. If the word value is a triangle number then we shall call the word a triangle word.
Using words.txt (right click and 'Save Link/Target As...'), a 16K text file containing nearly two-thousand common English words, how many are triangle words?

Anser:162
Time:223.895µs
*/
package main

import (
	"fmt"
	"io/ioutil"
	"strings"
	"time"
)

func main() {
	tstart := time.Now()
	const bound = 1e3
	s := [bound]bool{}
	for i := 1; ; i++ {
		num := i * (i + 1) / 2
		if num >= bound {
			break
		}
		s[num] = true
	}

	byt, _ := ioutil.ReadFile("p042_words.txt")
	str := strings.Replace(string(byt), "\"", "", -1)
	strs := strings.Split(str, ",")
	count := 0
	for _, v := range strs {
		sum := 0
		for _, vv := range v {
			sum += int(vv) - int('A') + 1
		}
		if s[sum] {
			count++
		}
	}
	fmt.Println(count)
	tend := time.Now()
	fmt.Println(tend.Sub(tstart))
}
